<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
         #box1 {
            width: 200px;
            height: 200px;
            padding: 5px; 
            border: 1px solid rgb(181, 51, 51);
            position : relative;
            background-color: rgb(0, 255, 187);
        }
        #box2 {
            margin: 10px;
            width: 300px;
            height: 300px;
            padding: 5px; 
            border: 1px solid rgb(181, 51, 71);
            background-color: rgb(255, 0, 47);
        }
    </style>
</head>
<body>
    <!-- 
        将页面绘制出来 ,
        box1 在box2上面 ,正常的文档流 
        html 文档流 和 css 结合样式生效 盒模型

    -->
    <div id="box1"></div>
    <div id="box2"></div>
</body>
</html>